assessing a photo taken to check quality etc

Im not sure if Ill be able to explain this very well so apologies if it sounds like im talking rubbish.

If I take a picture and then transfer it to the pc how can I check if the photo is in focus. Obv I know that the lcd will show if its compeletly out of focus but some photos look ok until I enlarge them and then I can see they werent in focus.

I know I should zoom or crop in but to what magnification should I go to in order to tell correctly and then would I be looking for a completely focused point or would I expect some softening. Also If I wanted to crop a photo for printing at what point would the cropping become pixelated.

Hope this makes sense.

--
a complete beginner, taken with a p&s and no pp

It depends on what tool you use to view the photo. When you zoom in, there's usually an indicator that shows you how far you've zoomed. Zoom until you see a 1:1 ratio or 100% view.

Cropping a photo isn't a good idea. You basically removing resolution. You should frame it right at the time of shooting, and perhaps do only minor cropping later, perhaps to fit into a different aspect ratio.

Cropping makes your printed photo look pixelated or not depending on the print size vs your image resolution. The math is simple. If you have a 8MP picture, and you crop out a half, then you're left with a 4MP picture, because that's 8 divided by 2.

Here's a basic guideline that I can tell you based on my experience. Don't crop beyond this guideline. However, in reality it can vary greatly because not all pixels are created equal (read the dpreview article on this). Also when you print very large, people tend to view these pictures at a greater distance, so even a pixelated picture might look good.

4"x6" print - need at least 1MP
5"x7" print - need at least 2MP
8"x10" print - need at least 4MP

karen77 said:

If I take a picture and then transfer it to the pc how can I check if the photo is > in focus. Obv I know that the lcd will show if its compeletly out of focus but > some photos look ok until I enlarge them and then I can see they werent in > focus.

Click to expand...

Espescially if we're talking JPEGs, you should view at 100% to determine sharpness of image. Not 200%, Not 104%, 100%. That will give you a one to one file to display ratio

karen77 said:

I know I should zoom or crop in but to what magnification should I go to in order to tell correctly and then would I be looking for a completely focused point or would I expect some softening.

Click to expand...

Depends on the inherant sharpness of your lens. To see how sharp you camera can be (as a point of reference for comparison) adjust your aperture down two stops from wide open and use a tripod + self timer/remote.

karen77 said:

Also If I wanted to crop a photo for printing at what point would the cropping become pixelated.

Click to expand...

I'm sorry but you have lost me here. Cropping doesn't affect pixelization of an image. Enlargment will but to what degree depends on the quality of your camera's output. You should go to a photo printing website and see what file sizes they recommend per cetain sized enlargements. I think that's what you might be asking about.
--



Don't forget to have fun.

karen77 said:

Im not sure if Ill be able to explain this very well so apologies if it sounds like im talking rubbish.

If I take a picture and then transfer it to the pc how can I check if the photo is in focus. Obv I know that the lcd will show if its compeletly out of focus but some photos look ok until I enlarge them and then I can see they werent in focus.

I know I should zoom or crop in but to what magnification should I go to in order to tell correctly and then would I be looking for a completely focused point or would I expect some softening. Also If I wanted to crop a photo for printing at what point would the cropping become pixelated.

Hope this makes sense.

--
a complete beginner, taken with a p&s and no pp

Click to expand...

Well, I try and read what you mean...

Whether a subject is in focus is quite easily detected when viewing on a large enough screen (I would not trust a camera-LCD for that, it's just too small).

Now there are a number of factors that can make it harder to check whether the subject is in focus or not:

• When there's enough contrast (in brightness or in color) any photo SEEMS sharper then when the contrast is low. (post processing will help, especially 'levels' or 'curves')
• The subject might be in focus but not sharp because of the subject moving (a faster shutter speed might help)
• The subject might be in focus but not sharp because of camera shake (a faster shutter speed, tripod or image stabilisation might help)
• The subject might be in focus but not sharp because there's false light falling into the lens (typically the sun shining on the front element of your lens)/ (a lens hood might help)
• The subject might be in focus but not sharp because of the lens is les sthan perfect (should not be the case, but it happens) (choosing a smaller aperture = higher number might help)
• The subject might not be rightly in focus because the AF focussed on another part than you would want, for instance AF on the ear is OOF for the eyes (on some cameras you can help the camera by choosing which AF point to use) (choosing a smaller aperture = higher number might help, with a P&S this problem will hardly ever occur)
• Only part of the subject is in focus, because the subject is quite large compared with the DOF, like in informal groups. Not likely with a P&S. (Composing differently may help, a smaller aperture could help)

And yes, some softening might be expected sometimes, but not too much.

Now to help diagnosing your problem(s), do post a few examples (not too small). If you don't know how, here's a guide:
http://forums.dpreview.com/forums/readflat.asp?forum=1002&message=33448875

--
All in my humble opionion of course!

If I seem to talk nonsense or you can't understand me, it's probably my English

Thank you for taking the time to understand my garbled message.

What you all have said makes sense to me and on some photos now ive gone through them they fall into certain cartegories.ie the af paoint was on the eye and thats why the rest of the face is soft, the av was too high meaning that only the tip of a nose was in focus and so on. I guess lots more practice is needed.

Heres 2 examples

This one is exactly what I wanted, my daughter to be in focus and the background slightly out of focus.



Then this one even though the flash went off just seems soft.



Is it because it was taken in low light with only the flash?

Im making sure that I either select my af point or only use the centre af to ensure that it doesnt focus on a point I dont want.
Thanks again

--
a complete beginner, taken with a p&s and no pp

karen77 said:

Thank you for taking the time to understand my garbled message.

What you all have said makes sense to me and on some photos now ive gone through them they fall into certain cartegories.ie the af paoint was on the eye and thats why the rest of the face is soft, the av was too high meaning that only the tip of a nose was in focus and so on. I guess lots more practice is needed.

Heres 2 examples

This one is exactly what I wanted, my daughter to be in focus and the background slightly out of focus.



Then this one even though the flash went off just seems soft.



Is it because it was taken in low light with only the flash?

Click to expand...

There could be several reasons, but unfortunately your EXIF data is being stripped, so it is difficult to see what camera setting were used. Perhaps you could post links to the images in Flickr, I think that Flickr is stripping the EXIF when it downsizes the images.

For a low light exposure the camera could be using a wide open aperture, slower shutter speed, and higher ISO setting – all of these could affect the image quality. At its widest aperture, the lens will produce softer images. At slower shutter speeds you can get some motion blur due to subject movement, providing there is enough ambient light in the exposure (the flash duration is very short, but there could be enough ambient light). And at higher ISO values the camera will try to reduce noise levels, but this can lead to less detail too.

Perhaps you could post links to the images in Flickr, I think that Flickr is stripping the EXIF when it downsizes the images.

Brian A.

karen77 said:

Then this one even though the flash went off just seems soft.



Is it because it was taken in low light with only the flash?

Click to expand...

My guess is that the low light and flash did NOT cause the softness of the faces of these children. As far as I can see the cubboard behind the kids is nicely sharp, what means this photo did not suffer from camera shake, but that was focussed on the cubboard in stead of on the kids. Or: you did focus on the kids but you have moved half a step forward after focussing and before taking the picture.

Persons in front of each other are a bit harder to focus as the distance to the two subjects is different. But I don't think that's the problem here.

--
All in my humble opionion of course!

If I seem to talk nonsense or you can't understand me, it's probably my English

That first shot is OUTSTANDING! Congratulations! I hope you have made an 8x10 print of that one. Really nice work (and, of course, a lovely child).

As far as the second shot is concerned, it looks like the focus is on the wooden ledge behind your kids. Your lens likely had trouble focusing in the low light conditions (did the flash "flicker" before the shot?). Given the circumstances, it's not a bad shot (better than none at all, right?). I can see how looking at this picture on your camera LCD would probably indicate acceptable focus.

To address your original question, if you really want to check focus and sharpness while you are shooting, you need to magnify a bit while reviewing the shot on your camera LCD. You can go to maximum magnification if you really want to nit-pick, but keep in mind you could be over-scrutinizing. A little softness at 100% view would likely not be visible in a small print or web image. If I'm worried about focus while I'm shooting, I'll magnify three or four "clicks" as I review on the camera. If I have any question about focus, I'll keep the image until I can review it on my monitor.

I crop my images and have prints made all the time, and they come out just fine. I'm usually pretty comfortable if I have 200 or more pixels per printed inch, but others will have differing opinions.

Keep on shooting -- I think you're doing great!

Regards,
Dave.

Hopefully this will provide the details.

http://www.flickr.com/photos/kbaby02/4088950243/meta/

Thanks for the compliment. I think I just struck lucky as it as a nice crisp autumn day which made the air real clear and each photo I took that day seemed to come out crisp and clear.

That said she is very beautiful and photogenic
Thank you for the tips on magnifying on the camera. I seem to forget about it.

The EXIF data shows that in this shot you were shooting in Tv mode (shutter priority) with a preset shutter speed of 1/20.

With Canon cameras when you are shooting in Av or Tv mode with a flash the camera assumes that you want fill flash - did you? If you want full flash use M or P modes - preferably M.

I think that the image is soft because you had too slow a shutter speed. You either have a little camera shake (does your lens have IS?) or some motion blur. I don't think that the flash, in fill mode, was able to freeze the motion or offset the camera shake.

I would try to keep the shutter speed above 1/50 if you are shooting people. If you wanted to use fill flash you would have had to increase the ISO to achieve this. There wouldn't have been any problem if you were using full flash but the image would have been harsher unless you have an external flash and can bounce.

By the way, if you are using flash don't focus and recompose. It often throws off the flash exposure.

I hope that this is of some help.
--
Chris R

I agree with Chris R-UK. You are using fill flash, and since fill flash is designed to use available light as much as it can, you have a relatively slow shutter speed and the maximum aperture for the chosen focal length. Lenses are rarely at their best wide open, and 1/20s isn’t fast enough for kids.

Under the same lighting, I would probably have tried ISO 800, 1/60s and f/6.3.

When not using fill flash (as Chris points out Av and Tv are auto fill flash modes on Canon cameras) and when the flash is the dominant light source, you can get away with longer shutter speeds, because the flash duration is extremely short. But when there is also a lot of ambient light in the image, camera shake and subject motion will affect the image.

On a different note, the EXIF claims you were using an external flash. If this is the case, then it is often better to shoot in landscape orientation and crop, rather than shooting in portrait orientation with the flash on the side. With the flash vertically over the camera, much of the harsh ugly flash shadow falls behind the subject and can’t been seen.

Brian A.

dave_lamb said:

That first shot is OUTSTANDING! Congratulations! I hope you have made an 8x10 print of that one. Really nice work (and, of course, a lovely child).

Click to expand...

That shot is superb! Clarity of detail, gentle colouring of tones and of course, subject.
Bravo!

--



Ananda
http://anandasim.mp

karen77 said:

Hopefully this will provide the details.
http://www.flickr.com/photos/kbaby02/4088950243/meta/

Click to expand...

As said, the artefact behind the kids is crisp/sharp, so there's nothing wrong with your Tv and time setting.

Now your EXIF tells you that 3 AF points found focus, makes me curious which ones. In ZoomBrowser (from the Canon CD with your camera) will show you what points that where. And if you did not move the camera after getting focus (like holding the shutter button halfly pressed waiting for that moment or recomposing) they will also show on WHAT was focussed. I would not be surprised this would be the piece of furniture that is in fact in focus.

In that case there's something to learn about using the AF on your Canon.

--
All in my humble opionion of course!

If I seem to talk nonsense or you can't understand me, it's probably my English

AdriaanMeijer said:

As said, the artefact behind the kids is crisp/sharp, so there's nothing wrong with your Tv and time setting.

Now your EXIF tells you that 3 AF points found focus, makes me curious which ones. In ZoomBrowser (from the Canon CD with your camera) will show you what points that where. And if you did not move the camera after getting focus (like holding the shutter button halfly pressed waiting for that moment or recomposing) they will also show on WHAT was focussed. I would not be surprised this would be the piece of furniture that is in fact in focus.

In that case there's something to learn about using the AF on your Canon.

Click to expand...

Now i'm slightly confused as the others have said my shutter speed was too slow.

I didnt realise that the software would show me that. TBH I loaded it on to the pc and havent used it as I couldnt get my head around what each differnt package actually did. Maybe I should take some time to learn if it will be really helpful to understanding my pictures.

AdriaanMeijer said:

--
All in my humble opionion of course!

If I seem to talk nonsense or you can't understand me, it's probably my English

Click to expand...

--
a complete beginner, taken with a p&s and no pp

karen77 said:

AdriaanMeijer said:

As said, the artefact behind the kids is crisp/sharp, so there's nothing wrong with your Tv and time setting.

Click to expand...

Now i'm slightly confused as the others have said my shutter speed was too slow.

Click to expand...

Well, yes, I understand that.

But just look at the photo! When camera shake, due to long shutter speed, was what was wrong, the camera shook and therefor ALL what's in the photo sould have been fuzzy. The wood-like thing (closet?) behind them kids clearly is UNSHAKEN, so the problem lies elsewhere.
As the closet is sharp and the kids are not, there are two possible problems:

1. the kids moved. Possible in theory and if they did a faster shutter speed would have helped. .... But it's not: This IS a flashed photo. A flash is as short as 1/1000 to less than 1/25000 of a second. Believe me, no way they have moved in that short a time.
2. The focussed distance is different from the subject distance. I'm quite confident that this is the case here.

By the way, flash potography can be difficult, for camera and/or shooter. The photo shows that the exposure of the photo was excellent and so are the colors (important for skin). Guess the camera and photographer team up nicely here.

karen77 said:

I didnt realise that the software would show me that. TBH I loaded it on to the pc and havent used it as I couldnt get my head around what each differnt package actually did. Maybe I should take some time to learn if it will be really helpful to understanding my pictures.

Click to expand...

Well, the software that came with the camera, be it not the most user friendly software ever build, surely is capable to do a lot of good. Showing the focus points is only one of the things it can do. Yes, when you get the change, install it and try and explore it.
Meanwhile keep coming back here, we still are here to assist you.

karen77 said:

(...) and no pp

Click to expand...

for searching what caused a problem that is good.

--
All in my humble opionion of course!

If I seem to talk nonsense or you can't understand me, it's probably my English

AdriaanMeijer said:

karen77 said:

AdriaanMeijer said:

As said, the artefact behind the kids is crisp/sharp, so there's nothing wrong with your Tv and time setting.

Click to expand...

Now i'm slightly confused as the others have said my shutter speed was too slow.

Click to expand...

Well, yes, I understand that.

But just look at the photo! When camera shake, due to long shutter speed, was what was wrong, the camera shook and therefor ALL what's in the photo sould have been fuzzy. The wood-like thing (closet?) behind them kids clearly is UNSHAKEN, so the problem lies elsewhere.
As the closet is sharp and the kids are not, there are two possible problems:

1. the kids moved. Possible in theory and if they did a faster shutter speed would have helped. .... But it's not: This IS a flashed photo. A flash is as short as 1/1000 to less than 1/25000 of a second. Believe me, no way they have moved in that short a time.

Click to expand...

Not the case when there is also ambient light involved, and clearly in this case, given the aperture, shutter speed, ISO, and the fact the camera was set for fill flash, there was plenty of ambient light involved in the exposure.

I remember a while back doing a memorial service, the indoor shots at were at 1/30 and 1/60s with fill flash. These were older people, and some of clearly ‘vibrated’ more than others, because some were blurred and others weren’t. And kids vibrate an awful lot.

It certainly isn’t camera shake, but kid-motion cannot be ruled out.

Brian A.

Hugowolf said:

Hugowolf said:

1. the kids moved. Possible in theory and if they did a faster shutter speed would have helped. .... But it's not: This IS a flashed photo. A flash is as short as 1/1000 to less than 1/25000 of a second. Believe me, no way they have moved in that short a time.

Click to expand...

Not the case when there is also ambient light involved, and clearly in this case, given the aperture, shutter speed, ISO, and the fact the camera was set for fill flash, there was plenty of ambient light involved in the exposure.

It certainly isn’t camera shake, but kid-motion cannot be ruled out.

Click to expand...

Ok, Brian, you are right. This can't be ruled out. I did not want to complicate the matter, but I should have said something like:

With flash the chances the kids moved causing blur are small. With longer shutter speeds they can move and so produce some blur, but I don't think that this is the case on this photo .
--
All in my humble opionion of course!

If I seem to talk nonsense or you can't understand me, it's probably my English